The present invention relates to machine tool installations employing apparatus for automatically loading and/or unloading workpieces from a worktable upon which the workpieces are supported during processing.
Machine tools which process sheet metal and like materials generally have one or more work stations and a work support table with a guidance system for gripping and moving the workpiece on the work support table, and/or for moving the work support table or a portion thereof relative to the work station(s). Generally, the movement of the workpiece in modern machines is controlled by a computer numeric control system to precisely position the workpiece relative to the work station for the machining operation.
As the speed and efficiency of these machines has increased, there has been increasing need for devices which would automatically load the workpieces to be processed onto, and/or remove the processed workpieces from, the work support table, thus minimizing the need for operator intervention and the attendant delay in processing time.
Various devices have been proposed for use in conjunction with such machine tools in order to facilitate the loading and unloading operation. Some of these devices require separate storage of each of the unprocessed workpieces and include elements to transport the workpieces in a horizontal plane. Although these devices have proven useful, there has remained a need for a relatively simple but effective loader/unloader which can be coupled to an existing machine tool installation and operate effectively under the control of the computer numeric control for the machine tool.
Accordingly, it is an object of the present invention to provide a novel loader/unloader for sheet metal and the like for use in conjunction with a machine tool having a work support table with at least a portion movable under control of the computer numeric control of the machine tool.
It is also an object to provide such a loader/unloader which not only delivers the unprocessed workpiece to the work support table of the machine tool but also removes the processed worksheet.
Another object is to provide such a loader/unloader which effects the unloading of the processed work sheet and the loading of a fresh workpiece for processing in a sequence which is rapid and highly effective.
It has now been found that the foregoing and related objects may be readily attained in a machine tool installation having a machine tool with a work support table for supporting sheet material for movement in a horizontal plane in X and Y axes. A workpiece guidance system is included for movement of the sheet material in one of the axes on the work support table, and at least a portion of the table is movable horizontally by moving means.
A sheet material loader and unloader is disposed adjacent to the machine tool, and includes a frame, a platform supported on the frame for vertical movement adjacent the work support table portion, and means for moving the platform vertically between a position above the horizontal plane of the work support table and a position therebelow.
Sheet material gripping means is mounted on the frame for movement from a position forwardly of the frame to a retracted position, and there is provided means for operating and moving the gripping means. Sheet engaging means depends from the platform for engaging the top sheet of a stack of sheets disposed therebelow, and means is provided for operating said sheet engaging means.
Control means controls the several moving, gripping, engaging and operating means to move a sheet material workpiece on the work support table of the machine tool to a position over the platform of the loader and unloader for engagement by the gripping means in its forward position. As the work table moves away, the workpiece drops onto the platform. The sheet engaging means is operable to engage a sheet and the platform is moved upwardly to move the engaged fresh sheet material workpiece to a position above the plane of the work support table, and then the sheet engaging means deposits the sheet on the work support table portion.
Preferably, the sheet engaging means on the platform comprises suction elements and suction drawing means connected thereto and under control of the control means. The workpiece guidance system of the machine tool includes clamps to grasp the adjacent edge portions of a sheet and they are operable under control of the control means. The gripping means includes clamps to grasp the adjacent edge portions of a sheet and they are operable under control of the control means.
The machine tool has a computer controlling the operation thereof and including the control means for the moving and gripping and engaging elements of the loader and unloader.
Preferably, the frame includes stationary side members and a carriage is supported on the stationary side members and mounts the platform. The carriage is movable vertically on the side members to effect the vertical movement of the platform.
The carriage has side members with horizontal guide arms on which the platform is mounted, and it also has a bridge extending over the platform. The sheet material gripping means depends from the bridge and is supported by the bridge and movable horizontally thereon.